"I, Michael Buesch, am one of the maintainers of the GPL'd Linux
wireless LAN driver for the Broadcom chip (bcm43xx). The Copyright holders of bcm43xx (which includes me) want to talk to you, OpenBSD bcw developers, about possible GPL license and therefore copyright violations in your bcw driver. We believe that you might have directly copied code out of bcm43xx (licensed under GPL v2), without our explicit permission, into bcw (licensed under BSD license)." The entire thread can be found here.

It may not be an official release, but according to my layman knowledge (inserting IANAL and all the other disclaimers here ... done) incorporating code samples into code that goes to a public accessible CVS server should qualify as distribtion.

And the GPL is crystal clear about distributing derived works.

In the light of [1]

Q: Is making and using multiple copies within one organization or company "distribution"?
A: No, in that case the organization is just making the copies for itself. As a consequence, a company or other organization can develop a modified version and install that version through its own facilities, without giving the staff permission to release that modified version to outsiders.

However, when the organization transfers copies to other organizations or individuals, that is distribution. In particular, providing copies to contractors for use off-site is distribution.

and to a lesser extend [2] and [3], I would guess, that an internal revision control system for the (Open)BSD project without access to the general public would have prevented this situation, if it really has arrived by accident.

EDIT: I don't suggest, that using an NDA to exploit the secnario in [3] should be a viable path for a FOSS project. But it is one method, if sealing of the CVS /SVN server from the public is not feasable / practicable either.

But such a construction would be very awkward for an open source project, as in the FOSS community development and distribution go hand in hand.
Feel free to correct me, if I'm wrong! Thanks in advance